Method of and apparatus for removing contaminants from surface of a substrate

ABSTRACT

A cleanling apparatus for removing contaminants from the surface of a substrate includes two parts: one which produces an aerosol including frozen particles and directs the aerosol onto the surface of the substrate to remove contaminants from the surface by physical force, and another part in which a fluid including a gaseous reactant is directed onto the surface of the substrate while the surface is irradiated to cause a chemical reaction between the reactant and organic contaminants on the surface, to chemically removing the organic contaminants. In the method of cleaning the substrate, the physical and chemical cleaning processes are carried out in a separate manner from one another so that the frozen particles of the aerosol are not exposed to the effects of the light used in irradiating the surface of the substrate. Therefore, the effectiveness of the aerosol in cleaning the substrate is maximized.

This is a divisional of U.S. patent application Ser. No. 10/012,564,filed Dec. 12, 2001, now U.S. Pat. No. 6,701,942, the entire contents ofeach which are hereby incorporated herein by reference for all purposesas if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of and apparatus for removingcontaminants, such as particles and organic material, from asemiconductor substrate or a liquid crystal display (LCD) substrate.

2. Description of the Related Art

In the process of manufacturing an integrated circuit (IC), such as amemory device or an LCD, the surface of a substrate of the IC may becontaminated. Contaminants on the surface of a substrate may includeorganic material, dust, residue, and metal contaminants. Suchcontaminants may be divided into two types: organic materials that canbe removed mainly by a chemical reaction and particles that can beremoved mainly by physical force. This contamination typically occurswhen the substrate is being stored or is in a stand-by state betweensuccessive processes. The contaminants may create defects thatultimately cause the integrated circuits to malfunction. For example,organic residue on the surface of a substrate may cause a defect in asubsequently formed thin film or may increase the contact resistance ofthe device.

Thus, a step of cleaning the surface of a substrate, such as a wafer, isattendant to each process performed in the manufacturing of anintegrated circuit such as memory device or an LCD. The cleaning isperformed to remove organic contaminants or contaminant particles fromthe surface of the substrate. Conventional wet cleaning techniques havebeen used for cleaning the surface of a substrate. It is well-known thatthese wet cleaning techniques are very effective in removing contaminantparticles from the surface of a substrate. Furthermore, the wet cleaningtechniques include the use of a spin brush during cleaning or anultrasonic or megasonic cleaner to enhance the cleaning effect.

Despite the significant efforts directed towards cleaning the surface ofa substrate, the effectiveness of conventional wet cleaning techniquesis quite limited when the circuit patterns of the memory device or LCDare extremely fine. For example, the use of a spin brush or anultrasonic cleaner may damage the fine patterns of a memory device or anLCD. Furthermore, although a spin brush or an ultrasonic cleaner in awet cleaning process may be effective in removing large contaminantparticles, they are hardly effective in removing particles on the orderof submicrons.

Furthermore, along with the miniaturization of the patterns, there is atrend in which a gate or a bit line includes metal such as tungsten (W).Many conventional wet cleaning processes would be detrimental to themetal. Therefore, wet cleaning a substrate on which such a gate or bitline has been formed is limited to rinsing the substrate with deionizedwater or a minimal cleaning using a stripper. In these cases, it becomesincreasingly difficult with any reliable degree to effectively prevent adefect from occurring during a fabrication process.

Recently, a number of new cleaning techniques have been developed forremoving contaminants such as particles or organic residue. For example,according to one approach, an aerosol including microscopic frozenparticles is sprayed over the surface of a substrate to removecontaminants from the surface of the substrate. U.S. Pat. No. 5,967,156issued on Oct. 19, 1999 to Peter H. Rose et al., and entitled“Processing A Surface,” describes a such a method.

More specifically, the patent discloses a method of removing foreignmaterial (for example, particulate contaminants such as dust and metals,and organic material such as photoresist and fingerprints, and residue)from the surface of a substrate by reacting a reactant gas with theforeign material. An aerosol including frozen particles is applied alongwith a flow of the reactant to the surface of the substrate to aid thereaction of the reactant gas with the foreign material. The surface ofthe substrate is irradiated with infrared (IR) or ultraviolet (UV) lightto heat the substrate, and thereby further aid the reaction of thereactant gas with the foreign material.

However, the effectiveness of the aerosol in cleaning the surface of thesubstrate is reduced because both the physical and chemical cleaningprocesses are performed simultaneously in the same place. Morespecifically, the ultraviolet or infrared light produced during thechemical cleaning process may reduce the effectiveness of the aerosolbecause ultraviolet and infrared light are radiant forms of energy.Therefore, the ultraviolet or infrared light is absorbed by the walls ofthe processing chamber and at the surface of the substrate, inparticular, by contaminants on the substrate surface or by the reactantfluid. Furthermore, the ultraviolet or infrared light may also beabsorbed by the nozzle from which the aerosol issues. Therefore, thetemperature inside the processing chamber may rise so much as topreclude frozen particles from issuing from the nozzle. Even if thefrozen particles do issue from the nozzle, there is high possibilitythat the frozen particles will evaporate before reaching the surface ofthe substrate. Thus, there are hardly any frozen particles to collidewith contaminant particles.

Accordingly, it is highly desirable to provide a method of and apparatusfor effectively removing contaminants, such as organic residues orparticles, from the surface of a substrate.

SUMMARY OF THE INVENTION

An object of the present invention is to solve the above-describedproblems by providing a method of and apparatus for effectively removingcontaminants, including particles and organic material, from the surfaceof a substrate in the process of fabricating an integrated circuit suchas a memory or a liquid crystal display (LCD).

Cleaning apparatuses of the present invention include means by whichparticles on the surface of a substrate are removed mainly by physicalforce using an aerosol comprising frozen particles, and means by whichorganic contaminants are chemically removed in a separate process by agaseous reactant and radiation providing activation energy for achemical reaction between the reactant and organic contaminants on thesurface of the substrate. That is, in the present invention, a physicalcleaning process using frozen particles is performed independently of achemical cleaning process using a fluid reactant and light so that theactivation energy required by the chemical cleaning process does notreduce the effectiveness of the frozen particles used to carry out thephysical cleaning process.

According to one aspect of the present invention, the cleaning apparatusincludes: a transfer chamber, a first cleaning chamber connected to thetransfer chamber, a reactant supplier associated with the first cleaningchamber so as to expose the surface of a substrate to a reactant withinthe first cleaning chamber, a light source also associated with thefirst cleaning chamber to irradiate the substrate and thereby supply theactivation energy required to cause a chemical reaction between thereactant and contaminants on the surface of the substrate, a secondcleaning chamber connected to the transfer chamber, and an aerosolgenerator associated with the second cleaning chamber for jetting anaerosol containing frozen particles onto the surface of the substratewithin the second cleaning chamber.

The light source may be an ultraviolet or infrared lamp that irradiatesthe substrate within the first cleaning chamber.

In a specific method according to the present invention executed inconjunction with this apparatus, a substrate is transferred from thetransfer chamber to one of the cleaning chambers whereupon one of thecleaning processes is performed therein, then the substrate istransferred to the other cleaning chamber via the transfer chamberwhereupon the other cleaning process is performed. Accordingly, theinfrared or UV light provided by the light source does not affect theefficacy of the frozen gas particles because the light and the frozengas particles are provided in separate spaces, i.e., the first andsecond cleaning chambers.

The aerosol generator may be a nozzle disposed above the inlet of thesecond cleaning chamber for jetting the aerosol onto the surface of thesubstrate as the substrate enters the second cleaning chamber.

According to another aspect of the present invention, the cleaningapparatus includes: a transfer chamber, a cleaning chamber connected tothe transfer chamber, an aerosol-generating nozzle disposed in thecleaning chamber for jetting an aerosol containing frozen particles ontothe surface of a substrate transferred into the cleaning chamber, areactant supplier that exposes the surface of the substrate to areactant within the cleaning chamber for chemically removingcontaminants from the surface of the substrate, and a laser beamgenerator that directs a laser beam onto the surface of the substratetransferred into the cleaning chamber in order to supply the activationenergy required to chemically react the reactant with the contaminants.

The aerosol-generating nozzle and the laser beam generator are orientedso that the aerosol is directed onto a region of the substrate separatefrom that onto which the laser beam is directed while the substrate isbeing transferred through (to or from) the cleaning chamber.Accordingly, the laser beam used for chemically cleaning the substratedoes not impinge the frozen particles used for physically cleaning thesubstrate.

In a specific method according to the present invention executed inconjunction with this apparatus, a substrate is transferred from thetransfer chamber into the cleaning chamber. As the substrate enters thecleaning chamber, the aerosol is jetted onto a leading region of thesubstrate surface and is physically cleaned (first cleaning process).The leading region then advances under the laser beam, whereby theactivation energy is provided at the leading region so that the leadingregion is chemically cleaned second cleaning process). The substrate isthen withdrawn from the cleaning chamber into the transfer chamber,whereby the leading region again is exposed to the aerosol jet (thirdcleaning process). In this way the entire substrate surface is bothphysically and chemically cleaned in a separate manner within the samecleaning chamber.

The cleaning methods thus can effectively remove contaminants, bothparticles and organic material, from the surface of the substrate duringthe fabricating of an integrated circuit such as a memory device or anLCD.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objectives and advantages of the present invention will becomemore apparent by describing in detail preferred embodiments thereof withreference to the attached drawings in which:

FIG. 1 is a plan view of a first embodiment of a cleaning apparatusaccording to the present invention;

FIG. 2 is a sectional view of a first cleaning chamber of the cleaningapparatus of FIG. 1;

FIG. 3 is a sectional view of a second cleaning chamber of the cleaningapparatus of FIG. 1;

FIG. 4 is a perspective view of an aerosol-generating nozzle of thecleaning apparatus of FIG. 1;

FIG. 5 is a plan view of a second embodiment of a cleaning apparatusaccording to the present invention;

FIG. 6 is a sectional view of a first cleaning chamber of the cleaningapparatus of FIG. 5; and

FIG. 7 is a schematic diagram of a substrate being cleaned by thecleaning apparatus of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which the preferred embodiments of thepresent invention are shown. In the drawings, the shapes of elements areexaggerated for clarity. In addition, like reference numerals designatelike elements throughout the drawings.

Referring to FIG. 1, the first embodiment of a cleaning apparatusaccording to the present invention includes one or more sets of cleaningchambers 200 and 300 connected to a central transfer chamber 100. Thetransfer chamber 100 sequentially transports and dispenses substrates400 to be cleaned to the cleaning chambers 200 and 300. The substrates400 may be supplied to or withdrawn from a loader (not shown) connectedto the transfer chamber 100. A robot (not shown) may be provided in thetransfer chamber 100. The substrates 400 are sequentially introducedinto the transfer chamber 100. The robot sequentially transports andloads the substrates 400 into the cleaning chambers 200 and 300 andsubsequently withdraws them from the cleaning chambers 200 and 300 intothe transfer chamber 100.

The cleaning chambers 200 and 300 provide a place in which contaminantson the surface of the substrate 400 are removed to clean the substratesurface. Here, the term “contaminants” collectively refers to all kindsof contaminants that may accumulate on the surface of the substrate 400as the integrated circuits are being manufactured or as the substrate400 is being transferred, stored or is standing by during the overallmanufacturing process. In the context of the present invention, thecontaminants can be thought of as being largely divided into two types:particles that are removable by physical force and organic material thatis removable by a chemical reaction. The surface of the substrate 400 iscleaned chiefly by a chemical reaction in the first cleaning chamber200, whereas the surface of the substrate 400 is cleaned chiefly byphysical force in the second cleaning chamber 300. In this case, thesecond cleaning chamber 300 is separate and discrete from the firstcleaning chamber 200.

Accordingly, the cleaning of the surface of the substrate 400 using achemical reaction is performed independently of the cleaning usingphysical force. Thus, the first cleaning chamber 200 may include areactant supplier 510 and an ultraviolet light source. The secondcleaning chamber 300 may include an aerosol generating nozzle 610.

More specifically, a reactant capable of forming a volatile byproductwith contaminants, in particular, organic contaminants, is directed ontothe surface of the substrate 400 to chemically remove the contaminantsfrom the surface of the substrate 400. The reactant may comprise oxygengas or ozone. In addition, the reactant may be directed onto the surfaceof the substrate 400 as a fluid flow.

Thus, the reactant supplier 510 in the first cleaning chamber 200 may bea nozzle or a gas port disposed above the surface of the substrate 400.In this case, the nozzle is preferably oriented such that the orificethereof faces the surface of the substrate 400, whereby a jet of thereactant gas issuing from the orifice impinges the surface of thesubstrate 400.

Furthermore, the nozzle may be located in the vicinity of the inlet ofthe first cleaning chamber 200 connected to the transfer chamber 100.This advantageously causes by-products of the cleaning reaction to beexhausted through an exhaust port 250 because the exhaust port 250 isdisposed opposite the inlet of the first cleaning chamber 200.

If oxygen gas is used as the reactant directed onto the surface of thesubstrate 400, the oxygen does not readily react with contaminants onthe surface of the substrate 400, in particular, with organiccontaminants. Therefore, additional activation energy is required tocause the oxygen gas to react with the organic contaminants. Theactivation energy may be provided by light, such as ultraviolet orinfrared light, directed onto the surface of the substrate 400.

For example, ultraviolet light may be generated by a light source (700in FIG. 2) such as an Hg discharge lamp disposed above the firstcleaning chamber 200. The generated ultraviolet light passes through aquartz window 210, which constitutes the upper wall of the firstcleaning chamber 200 or a chamber dome, and onto the substrate 400 inthe first cleaning chamber 200. The ultraviolet light generated by theHg discharge lamp may have a wavelength of 184.9 nm or 253.7 nm.

If ultraviolet light having a wavelength of 184.9 nm is directed ontothe surface of the substrate 400 in the first cleaning chamber 200, theultraviolet light actually may not be capable of decomposing organiccontaminants on the surface of the substrate 400, but may be absorbed bythe oxygen gas contained in the fluid flow of reactant jetted onto thesurface of the substrate 400. The oxygen gas absorbs the ultravioletlight and is activated to produce oxygen radicals or is transformed intoactivated ozone (O₃). The oxygen radicals or ozone reacts with theorganic contaminants to generate volatile by-products (actuallydecomposes the organic contaminants), and the generated by-products areexhausted through the exhaust port 250, whereby the surface of thesubstrate 400 is cleaned. In this way, the ultraviolet light having awavelength of 184.9 nm chiefly aids the reaction of the reactant withthe organic contaminants.

Ultraviolet light having a wavelength of 253.7 nm may be absorbeddirectly by organic contaminants on the surface of the substrate 400 todecompose the organic contaminants into CO₂ and H₂O.

When the chemical cleaning step performed in the first cleaning chamber200 involves the use of ultraviolet light, it is desirable to initiallyhave a predetermined soaking time. Because the ultraviolet or infraredradiation may heat the aluminum or stainless steel walls of the firstcleaning chamber 200, a cooling system for preventing an increase in thetemperature of the walls of the first cleaning chamber 200 may beinstalled along the outer circumference of the walls.

As described above, the surface of the substrate 400 transferred intothe first cleaning chamber 200 may be chemically cleaned by a fluid flowincluding oxygen gas along with ultraviolet radiation.

However, even after the surface of the substrate 400 has been cleaned inthis way, other types of contaminants, namely particulate material, mayremain on the surface of the substrate 400. Contaminants such asparticles need to be removed or cleaned by a physical mechanism.

To accomplish this, the cleaning apparatus according the presentinvention includes the second cleaning chamber 300 connected to thefirst cleaning chamber 200 via the transfer chamber 100. Hence, thesubstrate 400, which has been cleaned in the first cleaning chamber 200,can be successively transferred by the robot to the second cleaningchamber 300 through the transfer chamber 100. Thus, recontamination ofthe substrate surface is minimized. Alternatively, the substrate 400 maybe cleaned in the first cleaning chamber 200 after having been cleanedin the second cleaning chamber 300. That is, after having been cleanedby physical force in the second cleaning chamber 300, the substrate 400may be chemically cleaned in the first cleaning chamber 200.

As mentioned above, substrate 400 is cleaned in the second cleaningchamber 300 using physical force. As shown in FIGS. 1 and 3, thephysical force is generated by jetting an aerosol onto the surface ofthe substrate 400. In this case, the aerosol includes particles in theform of agglomerations of frozen gas particles. The frozen particles areprojected onto the surface of the substrate 400 by the gaseous portionof the aerosol.

The frozen particles entrained in the gaseous portion of the aerosolcollide with contaminant particles remaining on the surface of thesubstrate 400, thereby dislodging the contaminant particles from thesurface of the substrate 400. Although the aerosol jet is ineffective inremoving organic material, it exhibits an excellent cleaning effect onthose contaminant particles that are difficult to remove using achemical mechanism.

The frozen particles are produced by a heat exchanger 800. Preferably,an inert gas such as Ar is used for producing the aerosol. Some of theargon particles are frozen by the heat exchanger 800 and agglomerate.The frozen agglomerations of particles and the non-frozen gas particlesflow into the aerosol generating nozzle 610. This mixture of frozen andgaseous particles is jetted in the form of an aerosol through orifices615 of the nozzle 610. Preferably, the aerosol is jetted onto thesurface of the substrate 400 as it is being transferred into the secondcleaning chamber 300. Thus, the aerosol generating nozzle 610 isdisposed above an inlet of the second cleaning chamber 300 as shown inFIGS. 1 and 3.

In this case, even if the aerosol jet would only envelop a limitedregion of the surface of the substrate 400, the aerosol can nonethelessbe jetted over the entire surface of the substrate 400 by moving thesubstrate 400 from the transfer chamber 100 into the second cleaningchamber 300. To this end, the width of the aerosol jet, at the locationof the substrate surface, is preferably no less than the maximum widthof the substrate 400. Accordingly, as shown in FIG. 4, the aerosolgenerating nozzle 610 may include a plurality of nozzle orifices 615defined in and spaced along a rod-like nozzle body 611. The length ofthe nozzle body 611 may be at least the diameter or maximum width of thesubstrate 400. The nozzle orifices 615 face the surface of the substrate400 as the substrate passes below the aerosol generating nozzle 610,whereupon the aerosol emerging from the orifices 615 impinges thesurface of the substrate 400.

The frozen argon particles of the aerosol physically impact contaminantparticles on the substrate surface. The impact causes the contaminantparticles to be coercively removed from the surface of the substrate400. The substrate 400 may be passed back and forth below the aerosolgenerating nozzle 610 several times to ensure that the surface of thesubstrate 400 is sufficiently cleaned by the aerosol. Floatingcontaminant particles removed in this way are exhausted through anexhaust port 350 disposed at one end of the second cleaning chamber 300.

Meanwhile, before this cleaning process takes place, the second cleaningchamber 300 may be purged by nitrogen gas. The purge gas may becontinuously supplied while the cleaning process is being performed. Thepurge gas may be supplied via a gas port (not shown) provided in thesecond cleaning chamber 300. Alternatively, the purge gas may besupplied via a gas port (not shown) provided in the transfer chamber100, whereby the purge gas enters the second cleaning chamber 300 viathe transfer chamber 100. The purge gas may also be supplied to thefirst cleaning chamber 200.

The cleaning apparatus according to the first embodiment of the presentinvention, as described above, comprises separate and discrete places inwhich the substrate surface is physically cleaned by the aerosol jet andis chemically cleaned by a fluid reactant and radiant energy provided byinfrared or ultraviolet light. Accordingly, the effectiveness of theaerosol jet in cleaning the substrate surface is maximized.

Alternatively, in a second embodiment of a cleaning apparatus accordingto the present invention, as shown in FIGS. 5–7, the first and secondcleaning processes may be performed in the same chamber without reducingthe effectiveness of the aerosol jet in cleaning the surface of thesubstrate. This is made possible by using a laser to provide theactivation energy required to execute the chemical cleaning process.

Referring to FIGS. 5 and 6, the second embodiment of the cleaningapparatus according to the present invention includes one or morecleaning chambers 200′ disposed around a transfer chamber 100. Thetransfer chamber 100 sequentially transfers the substrates to be cleanedto the cleaning chamber 200′. A robot (not shown) may be provided in thetransfer chamber 100 to sequentially transfer and load the substrates400, which have been sequentially supplied to the transfer chamber 100,into the cleaning chamber 200′ and to collect the cleaned substrates 400from the cleaning chamber 200′.

The cleaning chamber 200′ provides a place in which contaminants on thesurface of the substrate 400 are removed. As with the case of the firstdisclosed embodiment, the term “contaminants” collectively refers to allkinds of contaminants that may accumulate on the surface of thesubstrate 400 as the integrated circuits are being manufactured or asthe substrate 400 is being transferred, stored or is standing by duringthe overall manufacturing process. However, unlike the first embodimentof the cleaning apparatus according to the present invention, the secondembodiment of the cleaning apparatus is configured such that physicaland chemical cleaning processes are performed in the same cleaningchamber 200′. Nevertheless, the activation energy, required forfacilitating the chemical cleaning process, does not prevent the frozenparticles of the aerosol from being formed or from cleaning the surfaceof the substrate.

More specifically, a reactant supplier 510 (e.g., a nozzle or a gasport) and a laser beam generator may be disposed in the cleaning chamber200′ to chemically remove contaminants from the surface of the substrate400. The reactant supplier 510 produces a fluid flow comprising areactant capable of forming volatile by-products through a chemicalreaction with contaminants on the surface of the substrate 400. Thereactant may include oxygen or ozone that are effective in removingorganic contaminants.

The reactant supplier 510 is installed in the cleaning chamber 200′ insuch a way as to direct the reactant onto the surface of the substrate400. Preferably, the reactant supplier 510 comprises a nozzle whoseorifice is directed toward the surface of the substrate 400 so that afluid jet of the reactant issuing from the nozzle impinges the surfaceof the substrate 400. Furthermore, the nozzle may be located in thevicinity of the inlet of the cleaning chamber 200′, i.e., adjacent thelocation at which the cleaning chamber 200′ is connected to the transferchamber 100. This advantageously facilitates the exhausting of theby-products of the cleaning reaction through an exhaust port 250 becausethe exhaust port 250 is disposed opposite the inlet of the cleaningchamber 200′.

Alternatively, the fluid flow comprising the reactant oxygen gas may beprovided in the transfer chamber 100. That is, a reactant supplier suchas a gas port is installed in the transfer chamber 100. The fluid flowcomprising the reactant is directed from the transfer chamber 100towards the cleaning chamber 200′, thereby providing the cleaningchamber 200′ with the reactant.

However, reactant gas, such as oxygen may not readily directly reactwith contaminants on the surface of the substrate 400, in particular,organic contaminants. Thus, activation energy is required to cause theoxygen to react with the organic contaminants. The activation energy maybe provided by a laser beam that irradiates the surface of the substrate400.

The laser beam may be generated by a laser beam generator including alaser 910, a lens 950, and a reflector 930 that reflects the laser beamfrom laser 910 through the lens 950. The laser beam is emitted into thecleaning chamber 200′ through a quartz window 210′ disposed on an upperwall of the cleaning chamber 200′. The laser beam is focused by the lens950 onto a predetermined focal plane, that coincides with the surface ofthe substrate 400 as the substrate is being transferred into thecleaning chamber 200′. The cross section of the laser beam at the focalplane, i.e., at the substrate surface, can be controlled by the lens950. In this case, the laser beam has an elongate cross section at thesurface of the substrate 400, as shown in FIG. 5. Therefore, althoughthe laser beam irradiates a limited region, substantially the entiresurface of the substrate 400 can be irradiated with the laser beam bymoving the substrate 400 across the path of the beam. In this case, thecross section of the laser beam at the surface of the substrate 400 hasa length greater than the width of the substrate 400 in one or moredirections.

The energy provided by the laser activates the oxygen gas or ozone toproduce oxygen radicals or activated ozone (O₃). Also, the lasersupplies the activation energy required to react the oxygen radicals oractivated ozone with organic contaminants on the substrate surface togenerate volatile by-products (actually decomposes the organiccontaminants), and the generated by-products are exhausted through theexhaust port 250, whereby the surface of the substrate 400 is cleaned.

As was mentioned above, the surface of the substrate 400 is also cleanedin the cleaning chamber 200′, using physical force. To this end, anaerosol-generating nozzle 610 may be disposed in the cleaning chamber200′. As in the first embodiment, the aerosol includes agglomerations offrozen gas particles, produced using a heat exchanger 800. Again, thegas is preferably argon. The aerosol of gaseous argon and frozenparticles of argon issue from the orifices 615 of nozzle 610. The frozenargon particles that reach the surface of the substrate 400 collide Withcontaminant particles remaining on the surface of the substrate 400,thereby dislodging the contaminant particles from the surface of thesubstrate 400. Floating contaminant particles removed in this way areexhausted through the exhaust port 250 at one end of the cleaningchamber 200′.

The aerosol-generating nozzle 610 is disposed above an inlet of thesecond cleaning chamber 300, as shown in FIGS. 5 and 6, to spray thesurface of the substrate 400 with the aerosol as the substrate 400 isbeing transferred into the cleaning chamber 200′ or is being withdrawnfrom the cleaning chamber 200′ into the transfer chamber. In this case,even if the aerosol jet has a cross-sectional area corresponding to onlya limited region on the surface of the substrate 400, the aerosol can bejetted over the entire surface of the substrate 400. Preferably, thewidth of the cross-sectional area of the aerosol jet is no less thanthat of the substrate 400. To this end, the aerosol-generating nozzle610 may be of the type previously described and shown in FIG. 4.

Meanwhile, before this cleaning process takes place, the cleaningchamber 200′ may be purged by nitrogen gas. The purge gas may becontinuously supplied while the cleaning process is being performed. Thepurge gas may be supplied via a gas port (not shown) provided in thecleaning chamber 200′. Alternatively, the purge gas may be supplied viaa gas port (not shown) provided in the transfer chamber 100, whereby thepurge gas enters the cleaning chamber 200′ via the transfer chamber 100.

As is clear from the description above, in the second embodiment of thecleaning apparatus according to the present invention, the laser beamand the aerosol are directed at separate locations within the cleaningchamber 200′ and hence, impinge discrete areas of the substrate surfaceat any given moment, as shown in FIGS. 5 and 6. More specifically, asshown in FIG. 7, the laser beam is emitted onto a region on thesubstrate surface different from that onto which the aerosol jet isdirected. The frozen argon particles 655 of the aerosol jet 600 are notexposed to the laser beam before reaching the surface of the substrate400 because laser beam is a highly directional or near-zero-divergencebeam.

Thus, the frozen argon particles 655 in the aerosol 600 are preventedfrom evaporating into a gas due to heating by laser beam irradiationbefore colliding with contaminant particles on the substrate surface.Furthermore, since the aerosol generating nozzle 610 is not actuallyexposed to the emitting laser beam, the aerosol generating nozzle 610 isnot heated by laser beam irradiation. Thus, the formation of an aerosolis not disturbed. Furthermore, since the laser beam is highlydirectional, the heating of the wall of the cleaning chamber 200′ due tothe laser beam irradiation or a temperature rise in the cleaning chamber200′ can be prevented.

Accordingly, physical cleaning by the frozen argon particles 655contained in the aerosol 600 can be effectively performed in thecleaning chamber 200′ as described above through chemical cleaning isalso performed therein.

According to a cleaning method using the cleaning apparatus according tothe second embodiment of the present invention, after the substrate 400is transferred to the transfer chamber 100, the substrate 400 istransferred from the transfer chamber 100 to the cleaning chamber 200′.There, the aerosol is jetted onto the surface of the substrate 400 asthe substrate 400 is moved under the aerosol-generating nozzle 610 tothereby clean the surface of the substrate 400 (first cleaning process).Subsequently, the surface of the substrate is exposed to a fluidcomprising a reactant and then is irradiated with a laser beam (secondcleaning process). Next, the substrate 400 is transferred from thecleaning chamber 200′ to the transfer chamber 100 to wherein the aerosolis again jetted onto the surface of the substrate 400 (third cleaningprocess). As a result, contaminants are effectively removed from thesurface of the substrate 400.

Finally, although the present invention has been particularly shown anddescribed with references to the preferred embodiments thereof, variouschanges in form and details may be made thereto without departing fromthe spirit and scope of the invention as defined by the appended claims.

1. A method of removing contaminants from the surface of a substrate,said method comprising: directing a fluid comprising a reactant, capableof chemically removing contaminants from, the surface of the substrate,onto the surface of the substrate, and irradiating the surface of thesubstrate with light to supply activation energy that causes a chemicalreaction of the reactant with contaminants on the surface of thesubstrate, thereby chemically cleaning the substrate; and jetting anaerosol comprising frozen gas particles onto the surface of thesubstrate to dislodge contaminants from the surface of the substrate,thereby physically cleaning the substrate, wherein over the entirecourse of said irradiating the surface of the substrate and said jettingof the aerosol onto the surface of the substrate, said irradiating andsaid jetting are carried out in a separate manner that prevents thefrozen particles of the aerosol from being evaporated by said light, andwherein said chemical cleaning of the substrate and said physicalcleaning of the substrate are performed in a common cleaning chamber,and said irradiating the surface of the substrate with light comprisesdirecting a laser beam onto a region on the surface of the substrateseparate from a region on the surface at which the aerosol is directed,whereby the laser beam and the aerosol impinge discrete areas of thesubstrate.
 2. The cleaning method of claim 1, wherein the reactantcomprises a gas selected from the group consisting of oxygen and ozone.3. The cleaning method of claim 1, wherein said jetting an aerosolcomprising frozen gas particles comprises freezing gaseous particles ofargon, whereupon the frozen argon particles agglomerate, and jetting thefrozen agglomerated particles towards the surface of the substrate. 4.The cleaning method of claim 1, wherein said jetting an aerosolcomprises spraying the aerosol over a width at least as great as themaximum width of the substrate, and moving the substrate relative to theaerosol until the entire surface of the substrate has been impinged bythe aerosol.